‘The Book of Henry’ is a misbegotten mishmash of several movies

Director Colin Trevorrow made a modest splash with his 2012 theatrical feature debut, “Safety Not Guaranteed,” an entertainingly quirky time-travel rom-com that couldn’t be pigeonholed. After a foray into more straightforward stuff with 2015’s “Jurassic World,” the cinematic mad scientist has returned to the laboratory with “The Book of Henry,” a movie so mystifyingly misbegotten that it makes Frankenstein — the monster, not the movie — seem unremarkable.

It’s the filmmaking equivalent of a monkey with the head of a goat, the tail of a fish, wings and teeny-tiny rat claws.

Working from a screenplay by Gregg Hurwitz, a TV writer (“V”) making his big-screen debut, Trevorrow starts off well enough with “Henry.” The title character, played by “Midnight Special’s” otherworldly Jaeden Lieberher, is an 11-year-old prodigy who runs his family’s finances while scribbling furiously in notebooks, haunting libraries, snapping Polaroids, talking on payphones and leaving audio notes to himself on a microcassette recorder. If there wasn’t a scene where someone can be seen using a smartphone — and there is — you’d swear the movie was set some time last century.

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Our out-of-time little hero, whose intellect seems to encompass all of human knowledge, including medical science, psychology, engineering and law, is also a compassionate soul, obsessing over the well-being of his classmate and next-door neighbor Christina (Maddie Ziegler). She’s a flinchy introvert who lives alone with her creepy widower stepfather — the aptly named Glenn Sickleman (Dean Norris), who also happens to be the town’s police commissioner.

This seemingly throwaway detail will come to loom large later on, along with the fact that a relative of Glenn’s (Philip Smreck) is the head of Child Protective Services.

Initially, the film doesn’t do much with the ominous, if nebulous, implications of the Sicklemans’ family dynamic, preferring to focus instead on the gently wacky comic potential of Henry’s family, which includes a cute little brother (“The Room’s” Jacob Tremblay) and their kooky single mom, Susan (Naomi Watts).

Susan, a waitress and aspiring children’s book author, is such a caricature of role reversal that she wastes her evenings playing violent, first-person-shooter video games while Henry — only ostensibly the dependent in the relationship — balances the checkbook.

For good measure, Sarah Silverman briefly pops up as Susan’s best friend and lovable lush, but then her character is quickly forgotten.

Only gradually does “Henry,” which early on registers as a solid if formulaic family dramedy, start to give way to something — or, rather, several somethings — that simply do not add up to a functioning whole. Waiting around the next plot turn are: a weepy medical melodrama; an uplifting romantic storyline involving Susan and a Doctor McDreamy character (Lee Pace); and, ultimately, a vigilante thriller so tonally inappropriate and out of left field that it seems spliced onto this movie from a completely different one.

It should be noted that “Henry” is well cast, with unforced and (mostly) relatable performances from its competent and — with the exception of Norris — appealing ensemble. Trevorrow, who is directing the 2019 “Star Wars” installment, knows what he is doing — or would, if he were making four or five separate films. Slick and polished to a high-gloss sheen, “Henry” is no hack job.

But be that as it may, the chimera-like mishmash of a movie ultimately cannot survive its many cross-purposes, which pull and tug against one another. In the end, “The Book of Henry” falls apart in a heap of loose pages, each one taken from a different script.